Enhancing the efficiency of CIGS thin film solar cells by inserting novel back surface field (SnS) layer

In this work, we propose a novel structure of solar cell based on copper-indium-gallium-diselenide CuIn_1-xGa_xSe₂ (CIGS) absorber layer by using SCAPS-1D (Solar Cell Capacitance Simulator of the University of Gent). This numerical simulation has been used to explore the possibility of higher efficiency and stable CdS/CIGS cell structures with (ZnO) as window layer, and (CdS) a buffer layer, (CIGS) absorber layer and (SnS) BSF layer. The optimal values to give maximum performance of the structure ZnO/CdS/CIGS/SnS, without and with the BSF layer (SnS), were determined. The study shows potential results for improvement of efficiency of solar cell when using the back surface field (BSF). It was observed that the proposed cell provided conversion efficiency of 25.29% (Voc = 0.79 V, Jsc = 36.43 mA/cm2, FF = 84.83). However the efficiency of cell reference (without BSF) is 17.99% (Voc = 0.62 V, Jsc = 36.03 mA/cm², FF = 80.23 %).